Wood stoves, air pollution, and climate


in Canada, Law, Politics, The environment

Mehrzad and his brother

Yesterday, Stella reminded me of one of the many trade-offs associated with climate change and environmental policies, generally. Montreal is considering a ban on new wood-burning appliances, on account of the local air pollution they cause. Wood certainly isn’t the cleanest burning stuff, especially when it is used in stoves that fail to achieve an ideal temperature and fuel-air mixture. That being said, burning sustainably harvested wood does not add greenhouse gasses to the atmosphere. This is because the trees being grown to supply the wood absorb as much carbon as the stoves are emitting.

In the long run, only biomass and renewables offer the prospect of unending energy. Encouraging the development of both is thus critical to making the transition to a zero-carbon global society. At the same time, other drawbacks do need to be considered: whether it’s the land and water use associated with biofuel production, the air pollution from biomass burning, or the damage caused by dams. These trade-offs illustrate how technology is never really a self-sufficient answer to environmental problems.

There are also further complexities on the climate side. What is the source of the wood? Is logging altering the albedo of the area, leading to greater or lesser absorption of solar radiation? Are the trees being felled absorbing atmospheric carbon at the same rate as the trees that will replace them? What are the climatic impacts of the physical cutting and transportation of the wood? What effect will the aerosols from the wood burning have on climate?

In the specific case of Montreal’s wood-burning stoves, I don’t know enough about the trade-offs involved to make a sensible suggestion. Perhaps it would be better to mandate that any wood-burning appliances meet emissions standards, rather than banning them completely, or perhaps that is infeasible for some reason and only a ban will work. For instance, it might just be too costly and impractical to create and enforce emissions standards for wood-fired devices. In the end, the business of living together in a finite world is inevitably one of compromise and politics.

{ 15 comments… read them below or add one }

R.K. March 17, 2009 at 11:39 am

Another environmental consideration is the habitat effects of producing wood to burn. Are there forests being felled, or plantations? What kind of species live in them? Is the logging causing sediment to be washed into streams? What lives in the streams?

Hella Stella March 17, 2009 at 11:39 am

I’m glad I could help contribue something to this blog that doesn’t involve puppies or inappropriate jokes.

Not that there’s anything wrong with those. They are my favourite things. after all.

Milan March 17, 2009 at 1:23 pm


That points to a further set of trade-offs in policy-making:

One the one hand, simple policies will probably produce unintended consequences in some areas.

On the other, complicated policies are more difficult to implement and operate. Making policies more complex also increases the temptation to do special favours to one group or another.

In the end, policies must be complex enough to avoid major injustice or inefficiency, while also being simple enough to be implementable and fair.


Keep the links, jokes, and puppy references coming.

Sarah March 17, 2009 at 2:08 pm

I’m amazed that anyone is surprised by this – it’s common practice in the UK for areas with high population density to ban the burning of smokey fuels in order to preserve decent air quality & these policies were introduced in response to the large number of deaths caused by smog earlier in the C20th (see http://news.bbc.co.uk/2/hi/health/2545747.stm & http://www.metoffice.gov.uk/education/secondary/students/smog.html for more info). I also strongly suspect that the name of the drink ‘London fog’ was inspired by these smogs – at any rate the drink is a milky grey-brown colour that I have never observed from natural fog.

Milan March 17, 2009 at 3:09 pm

It’s not surprising that wood burning contributes to local air pollution.

The question is: which policies best address all the relevant issues? Perhaps wood burning bans make sense in densely populated areas, while the regulation of stove types and wood sources is a more sensible approach for rural ones.

Tristan March 17, 2009 at 4:13 pm

I’m quite up-to-date on wood stove technology.

Modern wood stoves allow for a much more complete burn, because by circulating unburnt air into the area right above the fire, particles which would before simply have gone up the chimney unburnt, are burnt.

However, people are mostly idiots, and can’t be trusted in general to know how to use a woodstove. This means that wherever woodstoves are legal and cheap to use, many will be being used improperly. This produces not only more C02, but arguably more importantly, some pretty toxic pollution – the kind that burns your eyes. How bad this is depends on the weather, the worst is if there is an inversion, which for reasons I don’t entirely understand causes the gases to remain in the lower atmosphere, i.e., where you are breathing, rather than rising up to the sky. This can mean extremely bad news if your community is in a valley.

So, generally, while in many cases I would buy and use a woodstove, I would always support bans on their use if I lived in anything like a city.

Tristan March 17, 2009 at 4:14 pm

“That being said, burning sustainably harvested wood does not add greenhouse gasses to the atmosphere”

Does this mean that if I burn only deadfall, i.e. wood that died naturally and would rot if I did not burn it, that I am being carbon-neutral?

Milan March 17, 2009 at 4:20 pm

On a direct level, I think so.

There may, however, be second order consequences. For instance, burning deadfall wood rather than letting it rot might impoverish the soil, cutting future rates of biomass accumulation, and thus act as a net contributor of greenhouse gasses to the atmosphere.

In any case, burning wood that would otherwise rot is almost certainly better than heating using methane, oil, gas, and many forms of electricity.

Milan March 17, 2009 at 4:24 pm

The quick answer to all the second/third/fourth order problems is to say that we need to change the total intensity of human activity, as well as the specific forms it takes.

Quite probably, the mean sustainable lifestyle for our planet is significantly below what those in developed states already enjoy. Dealing with climate change and resource scarcity may well require that there be fewer people, living much less resource intensive lives.

Tristan March 17, 2009 at 5:51 pm

There is a further solution. My father has installed software in haystack burners which automatically email the provincial ministry so that a fine can be issued if the temperature of the burner drops below a threshold, or rises above another threshold.

It would be quite rational to install such a web-enabled device in home wood stoves – this is the only way to ensure that the modern stoves are used effectively. If people simply “stop down” the stove, even with the better combustion chamber, similar particulate emissions to poor wood stoves will ensue.

BuddyRich March 17, 2009 at 8:54 pm

Funny… when I am tired of urban living I want to move to the country and have enough land to setup an effective coppicing operation… If you can get about 7 acres of ash you can get yourself a cord of wood a year from the shoots on a 7 year grow cycle provided you only fell an acre at a time, indefinitely (or until those nasty ash borers get to em)… Its carbon neutral, and if you have 7 acres, the other pollutants are likely to not affect any of your neighbours to any great degree…

We have a wood burning fireplace here in the city though, and it wouldn’t surprise me if its actually negative efficiency in its heat output (likely not we did it resealed and new flue put in), but it does provide an unmatched ambiance, though it is not the primary heat source… Given that, I would hate to see it outlawed to get a new stove insert which is vastly more efficient than running a wood burning fireplace, which we eyed briefly to replace the fireplace… and any reasonably old house like in say the Glebe or Hintonburg is likely to have a fireplace.

Matt March 18, 2009 at 7:06 pm

This isn’t directly related to wood burning stoves, but instead gas burning stove tops. They are frequently cited as being nicer to cook with than electric, but of course their b- product is carbon dioxide. Would it be possible to make an electric stove that, in real time, creates hydrogen with electrolysis and then sends it to a burner? Maybe this could be useful for places that have clean electricity generation and a population of green-oriented gourmets.

Milan March 18, 2009 at 8:32 pm

Burning the gas directly for heat might actually be less CO2 intensive than burning gas or coal to generate electricity to run an electric stove.

. March 25, 2009 at 5:17 pm

Each in Its Place
On burning wood and gas
By Umbra Fisk
25 Mar 2009

I’m from Quebec and there is a movement underway to prohibit the new installation of wood burning fireplaces. I’m curious about how much carbon is produced by burning a cord of wood in a fireplace, compared to a tank of gasoline burned by an automobile.

Tristan February 6, 2010 at 10:45 am

Modern EPA certified stoves have extremely low NoX and black carbon emissions. Old stoves, or open fireplaces, are beyond awful.

The amount of carbon produced by burning a cord of wood in a fireplace is equal to the amount of carbon in the cord of wood. The interesting question is how much energy is captured to do useful work out of the reaction.

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